inconsistent overwrite warnings

Hey all --
Apologies if this topic has already been covered, but I've searched through the forums/support in several different ways been unable to find anyone with the exact same problem: when I drag and drop a file from my local browser to the remote browser, and a same-named file already exists on the remote machine, I get the "overwrite or skip?" warning only _the first time I do it for a given instance of SmartFTP_. Subsequent drag-and-drops don't trigger the message; SmartFTP just goes ahead and overwrites the remote file.

And yeah, I'm using the latest release (1.5.990), and the "drag and drop" matrix under Tools->Settings->File exist looks like this:
ask ask ask
ask ask ask
ask ask ask
...in other words, ask on all drag-and-drops.

Any ideas as to what's going on?

Thanks!
Ben